Field of the Present Invention
The present invention relates generally to non-resistive contact electrosonic sensor systems, and, in particular, to non-resistive contact sensors and sensor systems including devices and installations for detecting sonar signatures and electric or magnetic potentials.
Background
Auscultation is a widely used diagnostic procedure that provides a high degree of diagnostic power, is readily available, is non-invasive and can be performed at a relatively low cost. Typically, auscultation is performed using a stethoscope that acquires and conveys sounds or vibrations from the surface of a patient's body to an examiner's ear. More recently electronic stethoscopes have started replacing their mechanical counterparts. Electronic stethoscopes are typically based on a transducer that is capable of converting sounds or vibrations into electrical signals that are then amplified. Additionally, the detection capabilities of electronic stethoscopes are not limited to the constraints of human hearing. The effectiveness of human hearing varies substantially as a function of frequency and amplitude of the sounds to be detected. As a result, human hearing provides limited diagnostic capabilities because certain low frequency and/or low amplitude sounds that are useful for diagnostic purposes may be undetectable by humans. Electronic stethoscopes in combination with recent advances in signal processing and other technologies have resulted in the development of systems that can automatically acquire and analyze biological sounds or vibrations. Applications for electronic stethoscopes vary widely and include, for example, phonocardiology, phonopneumography and phonogastroenterology. In addition ultrasound stethoscopes have also been developed in response to the need to interrogate cardiac and breath sounds in environments where there may be high levels of ambient noise which can reach up to 110 dB during medical evacuation in a UH-60, BlackHawk helicopter.
Unfortunately, these solutions do not provide information on the electrical integrity of the heart or surrounding tissues. Traditionally resistive contact sensors are used which require electrical contact with the surface of individuals for effective transduction of the biological surface potential into an electronic format.
Combinations of acoustic stethoscopes and contact electrodes have been developed within the same device to effect the combined interrogation of structural and electrical function of the myocardium. This strategy however does not allow the flexibility that is needed in real life situations and the need for direct contact with the skin with the electrodes can be limiting especially when skin integrity is compromised secondary to injury or disease. Furthermore, resistive contact electrodes draw current away from the source, thus corrupting the signal, making reconstruction more technically challenging.
The problems with contemporary technologies may be summarized as follows. Sonar or other sonic sensing does not provide electrical information, and the results are corrupted by external acoustic and other sonic noise. Electric sensing, such as that involved in electrocardiograms, electromyograms, electroencephalograms, and the like, requires resistive contact, measuring the surface electric potential of the organism. In emergency situations, or when the surface is compromised, this approach can make it difficult to efficiently get a clear signal. Also, due to the resistive contact, the signal is drawn away from the source, making signal reconstruction difficult. Finally, existing electric and sonar and other sonic combinations require resistive contact, thus measuring only the surface potential and drawing the signal away from the source. In view of these problems, a need exists for an improved combination of electric and acoustic sensing.